Rotational symmetry breaking at the incommensurate charge-density-wave transition in Ba(Ni, Co)2(As, P)2: possible nematic phase induced by charge/orbital fluctuations

Nematic phase transitions in high-temperature superconductors have a strong impact on the electronic properties of these systems. BaFe2As2, with an established nematic transition around 137 K induced by magnetic fluctuations, and BaNi2As2, a nonmagnetic analog of BaFe2As2 with a structural transitio...

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Main Authors: Merz, Michael (Author) , Wang, Liran (Author) , Wolf, Thomas (Author) , Nagel, Peter (Author) , Meingast, Christoph (Author) , Schuppler, Stefan (Author)
Format: Article (Journal)
Language:English
Published: 16 November 2021
In: Physical review
Year: 2021, Volume: 104, Issue: 18, Pages: 1-16
ISSN:2469-9969
DOI:10.1103/PhysRevB.104.184509
Online Access:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1103/PhysRevB.104.184509
Verlag, lizenzpflichtig, Volltext: https://link.aps.org/doi/10.1103/PhysRevB.104.184509
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Author Notes:Michael Merz, Liran Wang, Thomas Wolf, Peter Nagel, Christoph Meingast, and Stefan Schuppler
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Summary:Nematic phase transitions in high-temperature superconductors have a strong impact on the electronic properties of these systems. BaFe2As2, with an established nematic transition around 137 K induced by magnetic fluctuations, and BaNi2As2, a nonmagnetic analog of BaFe2As2 with a structural transition in the same temperature range, share a common tetragonal aristotype crystal structure with space-group type I4/mmm. In contrast to BaFe2As2 where collinear stripe magnetic order is found for the orthorhombic low-T phase, a unidirectional charge density wave together with (distorted) zigzag chains are observed for the triclinic low-T phase of BaNi2As2. Here we show that between the high- and low-T phases of Ba(Ni,Co)2(As,P)2 an additional phase with broken fourfold symmetry and dxz orbital order exists which is a promising candidate for charge/orbital-fluctuation-induced nematicity. Moreover, our data suggest that the enhanced Tc found for Ba(Ni,Co)2(As,P)2 for higher Co or P substitution levels might result from suppression of the (distorted) zigzag chains by reducing the contribution of the dxy orbitals.
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Physical Description:Online Resource
ISSN:2469-9969
DOI:10.1103/PhysRevB.104.184509